Health care insurance premiums will be going up for tens of millions of Americans under Obamacare -- not down as the president promised.

National Journal conducted an analysis of the new plans and found that for the vast majority of Americans, insurance premiums will be higher in Obamacare exchanges than they're paying now for benefits sponsored by their employers.

Supporters of the law say the rate hikes will only apply to those covered by their employers.

But some businesses are planning to drop all or part of their health coverage because of Obamacare.

"To any small employer, it's a no-brainer," Devon Herrick, a senior fellow at the National Center for Policy Analysis, told the Journal.

"If workers can get better coverage that's subsidized, it makes sense for the employer to stop providing health insurance."